3 1/4 ounces bittersweet chocolate (60 to 64 percent cacao), chopped
1/4 teaspoon coarse salt
1 cup heavy cream, divided
1 teaspoon unflavored gelatin
2 tablespoons sugar, divided
3 large egg yolks
1/4 cup creme fraiche
Nonstick cooking spray
3/4 cup unsweetened cocoa powder
1 large egg
1 large egg white
1/2 cup plus 1 tablespoon all-purpose flour
1/2 cup plus 1 tablespoon cake flour (not self-rising)
3/4 teaspoon baking soda
1/4 teaspoon baking powder
1 1/4 cups packed dark-brown sugar
6 tablespoons (3/4 stick) unsalted butter, room temperature
1/4 teaspoon vanilla paste or pure vanilla extract
1/4 teaspoon coarse salt
1/4 cup plus 2 tablespoons buttermilk
2 tablespoons cocoa nibs
1 tablespoon finely ground espresso beans
Chocolate Crumb Base
Black Pepper Icing